The present invention relates to a dummy bar wagon for an installation for the continuous casting of steel and similar molten metals, in which the dummy bar is flexible and is of the type having a linked structure like a chain.
More particularly, the invention concerns a wagon provided with a chain carrying first and second dog-shaped carriers arranged to engage respective seats formed close to the head and the tail of a dummy bar to load the dummy bar onto the wagon at one end thereof, move it towards the opposite end, and unload it from the wagon for insertion from above into a mold of a continuous-casting installation.
It is known that, after steel casting has been started in an installation of the type under consideration, the dummy bar is removed from the roller track which extends downstream of the mold, and is brought close to the mold to be inserted therein from above at the beginning of a new casting. More particularly, the dummy bar is moved away from the roller track by means of a winch which lifts it and holds it suspended vertically in a position spaced from the ingot mold, generally called the dummy bar recovery station. A wagon movable on rails between the mold and the dummy bar recovery station transfers the dummy bar from the station to the mold when required.
The wagon is generally provided with apparatus and/or devices which are able to take the dummy bar from the holding members (hooks) of the lifting winch, load it onto the wagon and, when the wagon is close to the mold, unload it from the carriage, introducing it from above into the mold where it holds it suspended until it is locked by the usual means (nipping rollers) provided for this purpose. Generally, an endless chain (or several chains) is used for these operations, the chain extending longitudinally on the wagon, which supports it by rollers or driven wheels, and being provided with take up members for pulling and releasing the dummy bar. These members are, for example, constituted by two or more dog-shaped carriers fixed to the chain and formed so as to engage respective seats formed in the dummy bar rod.
The practicability, effectiveness, and timing of operation of these members have until now depended on the precision and regularity of operation of relatively complex mechanisms provided for their control and actuation.
The regularity and reliability of the operation of these mechanisms are often jeopardized by the weight and bulk of the dummy bar, which are known to be considerable, by its flexibility, and hence the known difficulties presented by its handling.
Other technical disadvantages of these mechanisms are constituted by the difficulty of their timing with other moving members, and the frequency of control and maintenance operations which they require.